Apr 3 2019
It is a well-known fact that chameleons have the ability to change their colors to match their surroundings. Now, a similar kind of phenomenon can be observed in a new group of smart materials known as metamaterials.
(Image credit: Springer)
However, a major problem is that these metamaterials are not capable of responding to proximal objects because of their physical properties. Hence, to overcome this drawback, Chinese physicists have created what is referred to as “metashells.” These are hollow shells composed of metamaterials and have the ability to carry materials in their core. One benefit is that their physical properties, for example, permittivity—the degree to which a material is able to store charge inside an electrical field—tends to alter with the electromagnetic characteristics of the material they encompass. In a new hypothetical work reported in EPJ B, Jiping Huang and Liujun Xu from Fudan University in Shanghai, China, explained how they were able to create a whole class of these novel chameleon-like metashells.
It is well known that metamaterials possess negative refraction index—for electromagnetic waves as well as other wave phenomena, for example, sound waves.
The direction of incoming waves can be radically changed by a negative index, which also “bends them away.” However, the permittivity of the present-day metamaterials—which, along with permeability, establishes their refraction index—happens to be a static trait, that is, they do not acclimatize to their environment. Now, all that can possibly be changed by the metashells.
Physicists Liujun Xu and Jiping Huang meticulously measured the metashells’ effective properties, and were able to render these properties equivalent to those of the material kept within their core. The metashells consequently became adaptive. The authors conducted hypothetical analyses, which were additionally verified by simulations.
Intelligent metashells like these can perhaps serve as a multipurpose material to meet a range of permittivity needs under various conditions. Experimental research and industrial applications will be the focus of the next stages.